坑中坑基坑变形规律相似实验与数值模拟研究

Deformation analysis of pit-in-pit based on similar experiment and numerical simulation

"坑中坑"基坑支护是新时期典型工程问题,但更多依赖于工程经验。文中针对"坑中坑"基坑的工程问题,现场取样并实验室建立尺寸为1.77m×1.72m×1.35m的物理模型,分析外坑和内坑的水平竖直变形规律,基于FLAC3D数值模拟了支护条件下基坑的应力分布及位移变化。研究得出,基坑变形随深度变化,水平变形呈现"纺锤"形,竖直变形逐渐减小,A方向的变形最大,B方向次之,D方向再次之,C方向最小。内外坑土体卸荷状态叠加,增大了基坑的整体应力梯度,导致土体变形量的增大。

Support of pit-in-pit is a typical engineering problem nowadays. Its design depended on experience more often.Base on a specific project,a physical model with dimension of 1. 77 m× 1. 72 m × 1. 35 m was construct by sampling soil in situ. The regularity of the pit deformation was obtained by analyzing horizontal and vertical strain of soil mass. Distribution of maximum principle stress and displacement variation in pit was examined by numerical simulation based on FLAC3 D. The deformation of the pit varied with its depth,and horizontal strain curve was fusiform shape and vertical strain decreased with depth. The deformation of the pit in A-direction was at maximum value and followed by B-direction,D-direction and C-direction. It is the state superposition that increased the stress grade and resulted in large deformation value,inner pit and outer pit unloading.